This invention relates to medico-surgical apparatus.
One technique for performing a percutaneous tracheostomy involves a needle carrying a cannula. An initial cut is made with a scalpel through the skin of the neck and the needle is pushed through neck tissues and the anterior wall of the trachea so that the tip of the needle and the cannula locate in the trachea. The needle is then pulled out to leave the cannula in place. A guidewire is inserted through the cannula, which is then removed. A dilator is slid along the guidewire to expand the opening through the tissue sufficiently to receive a tracheostomy tube. The dilator may take various forms, such as an expanding forceps, as described in EP0505390, or a tapering dilator or series of tapering dilators.
One problem with this technique is that, the needle must be sufficiently long to accommodate the cannula, making it long enough to contact the posterior wall of the trachea. This can lead to damage to the wall of the trachea if used incorrectly. In extreme cases, the needle could be pushed through the posterior wall of the trachea into the oesophagus, causing the guidewire and dilators to be inserted in the oesophagus.
It is an object of the present invention to provide alternative medico-surgical apparatus.
According to one aspect of the present invention there is provided a tracheostomy assembly including a needle having a pointed first end adapted for insertion through neck tissue into the trachea, a cannula extending along the outside of the needle and a stop mounted on the cannula, the stop having a first end adapted to limit the extent of insertion of the assembly in the trachea, and the stop being removable from the cannula when the cannula is located in the trachea.
The stop is preferably a clip-fit on the cannula and is removable laterally. The stop is preferably of channel shape. The cannula may have an enlarged portion towards its rear end, the stop being adapted to engage the enlarged portion. The enlarged portion is preferably a hub. The needle preferably has an enlarged portion towards its rear end, which may be a hub. The first end of the stop is preferably spaced rearwardly of the first end of the needle by substantially 20 mm. The stop may have a laterally extending flange at its first end. The stop may be held on the cannula by resilience of the stop.
According to another aspect of the invention there is provided a stop for a tracheostomy assembly according to the above one aspect of the invention.
A percutaneous tracheostomy assembly according to the present invention, will now be described, by way of example, with reference to the accompanying drawing.